I've been using mine on coolant for years with no ill effects. The thinnest suction tube has no problem snaking past the oil or transmission cooler and getting to the bottom of the radiator tank. It drains just as well as the petcock (when the petcock works), and doesn't spill a drop. I even use it for gasoline, which they warn against, but I think it's just a safety thing, rather than something that will cause damage.

It's also super handy for draining transmission pans before removal, and does a pretty respectable job of vacuum bleeding brakes.

 

I can visualize it in a following way:
- open the cap of a coolant tank and provide a water flow using the garden hose
- detach the bottom hose as a drain
- give it a crank and run till all dirt comes out (check the bottom of a dishpan)
Seems legit.
Yup, I know, the engines love the temperature of 185F and it's definitely not a water from a garden hose. But they don't like the crap into a cooling systems way more.
Am I still into a reality...?
Cheers, Mike

 

Gosh, You have surprised me. I wouldn't expect You can drain the coolant too. I am gonna definitely look for one of these on a local market. Thanks.

 

Glad I could help!